A gaseous constituent supply device for supplying an air vortex ring containing a gaseous constituent includes a first chamber for holding the gaseous constituent, a compressing portion for compressing air in the first chamber, and a second chamber communicating with the first chamber through an opening. A method for producing said formulation. The component : a copolymer having a maleimide structural unit of Formula and a repeating structural unit of Formula. The second input indicates a bandwidth of the allocated band. The helmet also comprises adjustable tensioning means disposed at the rear of the helmet configured to tension the inner helmet and liner onto the pilot’s head, to secure and locate the helmet in place on the pilot’s head.